2 * RTC class driver for "CMOS RTC": PCs, ACPI, etc
4 * Copyright (C) 1996 Paul Gortmaker (drivers/char/rtc.c)
5 * Copyright (C) 2006 David Brownell (convert to new framework)
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
14 * The original "cmos clock" chip was an MC146818 chip, now obsolete.
15 * That defined the register interface now provided by all PCs, some
16 * non-PC systems, and incorporated into ACPI. Modern PC chipsets
17 * integrate an MC146818 clone in their southbridge, and boards use
18 * that instead of discrete clones like the DS12887 or M48T86. There
19 * are also clones that connect using the LPC bus.
21 * That register API is also used directly by various other drivers
22 * (notably for integrated NVRAM), infrastructure (x86 has code to
23 * bypass the RTC framework, directly reading the RTC during boot
24 * and updating minutes/seconds for systems using NTP synch) and
25 * utilities (like userspace 'hwclock', if no /dev node exists).
27 * So **ALL** calls to CMOS_READ and CMOS_WRITE must be done with
28 * interrupts disabled, holding the global rtc_lock, to exclude those
29 * other drivers and utilities on correctly configured systems.
32 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34 #include <linux/kernel.h>
35 #include <linux/module.h>
36 #include <linux/init.h>
37 #include <linux/interrupt.h>
38 #include <linux/spinlock.h>
39 #include <linux/platform_device.h>
40 #include <linux/log2.h>
43 #include <linux/of_platform.h>
45 #include <asm/i8259.h>
48 /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
49 #include <linux/mc146818rtc.h>
52 struct rtc_device *rtc;
55 struct resource *iomem;
56 time64_t alarm_expires;
58 void (*wake_on)(struct device *);
59 void (*wake_off)(struct device *);
64 /* newer hardware extends the original register set */
69 struct rtc_wkalrm saved_wkalrm;
72 /* both platform and pnp busses use negative numbers for invalid irqs */
73 #define is_valid_irq(n) ((n) > 0)
75 static const char driver_name[] = "rtc_cmos";
77 /* The RTC_INTR register may have e.g. RTC_PF set even if RTC_PIE is clear;
78 * always mask it against the irq enable bits in RTC_CONTROL. Bit values
79 * are the same: PF==PIE, AF=AIE, UF=UIE; so RTC_IRQMASK works with both.
81 #define RTC_IRQMASK (RTC_PF | RTC_AF | RTC_UF)
83 static inline int is_intr(u8 rtc_intr)
85 if (!(rtc_intr & RTC_IRQF))
87 return rtc_intr & RTC_IRQMASK;
90 /*----------------------------------------------------------------*/
92 /* Much modern x86 hardware has HPETs (10+ MHz timers) which, because
93 * many BIOS programmers don't set up "sane mode" IRQ routing, are mostly
94 * used in a broken "legacy replacement" mode. The breakage includes
95 * HPET #1 hijacking the IRQ for this RTC, and being unavailable for
98 * When that broken mode is in use, platform glue provides a partial
99 * emulation of hardware RTC IRQ facilities using HPET #1. We don't
100 * want to use HPET for anything except those IRQs though...
102 #ifdef CONFIG_HPET_EMULATE_RTC
103 #include <asm/hpet.h>
106 static inline int is_hpet_enabled(void)
111 static inline int hpet_mask_rtc_irq_bit(unsigned long mask)
116 static inline int hpet_set_rtc_irq_bit(unsigned long mask)
122 hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
127 static inline int hpet_set_periodic_freq(unsigned long freq)
132 static inline int hpet_rtc_dropped_irq(void)
137 static inline int hpet_rtc_timer_init(void)
142 extern irq_handler_t hpet_rtc_interrupt;
144 static inline int hpet_register_irq_handler(irq_handler_t handler)
149 static inline int hpet_unregister_irq_handler(irq_handler_t handler)
156 /*----------------------------------------------------------------*/
160 /* Most newer x86 systems have two register banks, the first used
161 * for RTC and NVRAM and the second only for NVRAM. Caller must
162 * own rtc_lock ... and we won't worry about access during NMI.
164 #define can_bank2 true
166 static inline unsigned char cmos_read_bank2(unsigned char addr)
168 outb(addr, RTC_PORT(2));
169 return inb(RTC_PORT(3));
172 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
174 outb(addr, RTC_PORT(2));
175 outb(val, RTC_PORT(3));
180 #define can_bank2 false
182 static inline unsigned char cmos_read_bank2(unsigned char addr)
187 static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
193 /*----------------------------------------------------------------*/
195 static int cmos_read_time(struct device *dev, struct rtc_time *t)
198 * If pm_trace abused the RTC for storage, set the timespec to 0,
199 * which tells the caller that this RTC value is unusable.
201 if (!pm_trace_rtc_valid())
204 /* REVISIT: if the clock has a "century" register, use
205 * that instead of the heuristic in mc146818_get_time().
206 * That'll make Y3K compatility (year > 2070) easy!
208 mc146818_get_time(t);
212 static int cmos_set_time(struct device *dev, struct rtc_time *t)
214 /* REVISIT: set the "century" register if available
216 * NOTE: this ignores the issue whereby updating the seconds
217 * takes effect exactly 500ms after we write the register.
218 * (Also queueing and other delays before we get this far.)
220 return mc146818_set_time(t);
223 static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
225 struct cmos_rtc *cmos = dev_get_drvdata(dev);
226 unsigned char rtc_control;
228 if (!is_valid_irq(cmos->irq))
231 /* Basic alarms only support hour, minute, and seconds fields.
232 * Some also support day and month, for alarms up to a year in
236 spin_lock_irq(&rtc_lock);
237 t->time.tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
238 t->time.tm_min = CMOS_READ(RTC_MINUTES_ALARM);
239 t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM);
241 if (cmos->day_alrm) {
242 /* ignore upper bits on readback per ACPI spec */
243 t->time.tm_mday = CMOS_READ(cmos->day_alrm) & 0x3f;
244 if (!t->time.tm_mday)
245 t->time.tm_mday = -1;
247 if (cmos->mon_alrm) {
248 t->time.tm_mon = CMOS_READ(cmos->mon_alrm);
254 rtc_control = CMOS_READ(RTC_CONTROL);
255 spin_unlock_irq(&rtc_lock);
257 if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
258 if (((unsigned)t->time.tm_sec) < 0x60)
259 t->time.tm_sec = bcd2bin(t->time.tm_sec);
262 if (((unsigned)t->time.tm_min) < 0x60)
263 t->time.tm_min = bcd2bin(t->time.tm_min);
266 if (((unsigned)t->time.tm_hour) < 0x24)
267 t->time.tm_hour = bcd2bin(t->time.tm_hour);
269 t->time.tm_hour = -1;
271 if (cmos->day_alrm) {
272 if (((unsigned)t->time.tm_mday) <= 0x31)
273 t->time.tm_mday = bcd2bin(t->time.tm_mday);
275 t->time.tm_mday = -1;
277 if (cmos->mon_alrm) {
278 if (((unsigned)t->time.tm_mon) <= 0x12)
279 t->time.tm_mon = bcd2bin(t->time.tm_mon)-1;
286 t->enabled = !!(rtc_control & RTC_AIE);
292 static void cmos_checkintr(struct cmos_rtc *cmos, unsigned char rtc_control)
294 unsigned char rtc_intr;
296 /* NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
297 * allegedly some older rtcs need that to handle irqs properly
299 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
301 if (is_hpet_enabled())
304 rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
305 if (is_intr(rtc_intr))
306 rtc_update_irq(cmos->rtc, 1, rtc_intr);
309 static void cmos_irq_enable(struct cmos_rtc *cmos, unsigned char mask)
311 unsigned char rtc_control;
313 /* flush any pending IRQ status, notably for update irqs,
314 * before we enable new IRQs
316 rtc_control = CMOS_READ(RTC_CONTROL);
317 cmos_checkintr(cmos, rtc_control);
320 CMOS_WRITE(rtc_control, RTC_CONTROL);
321 hpet_set_rtc_irq_bit(mask);
323 cmos_checkintr(cmos, rtc_control);
326 static void cmos_irq_disable(struct cmos_rtc *cmos, unsigned char mask)
328 unsigned char rtc_control;
330 rtc_control = CMOS_READ(RTC_CONTROL);
331 rtc_control &= ~mask;
332 CMOS_WRITE(rtc_control, RTC_CONTROL);
333 hpet_mask_rtc_irq_bit(mask);
335 cmos_checkintr(cmos, rtc_control);
338 static int cmos_validate_alarm(struct device *dev, struct rtc_wkalrm *t)
340 struct cmos_rtc *cmos = dev_get_drvdata(dev);
343 cmos_read_time(dev, &now);
345 if (!cmos->day_alrm) {
349 t_max_date = rtc_tm_to_time64(&now);
350 t_max_date += 24 * 60 * 60 - 1;
351 t_alrm = rtc_tm_to_time64(&t->time);
352 if (t_alrm > t_max_date) {
354 "Alarms can be up to one day in the future\n");
357 } else if (!cmos->mon_alrm) {
358 struct rtc_time max_date = now;
363 if (max_date.tm_mon == 11) {
365 max_date.tm_year += 1;
367 max_date.tm_mon += 1;
369 max_mday = rtc_month_days(max_date.tm_mon, max_date.tm_year);
370 if (max_date.tm_mday > max_mday)
371 max_date.tm_mday = max_mday;
373 t_max_date = rtc_tm_to_time64(&max_date);
375 t_alrm = rtc_tm_to_time64(&t->time);
376 if (t_alrm > t_max_date) {
378 "Alarms can be up to one month in the future\n");
382 struct rtc_time max_date = now;
387 max_date.tm_year += 1;
388 max_mday = rtc_month_days(max_date.tm_mon, max_date.tm_year);
389 if (max_date.tm_mday > max_mday)
390 max_date.tm_mday = max_mday;
392 t_max_date = rtc_tm_to_time64(&max_date);
394 t_alrm = rtc_tm_to_time64(&t->time);
395 if (t_alrm > t_max_date) {
397 "Alarms can be up to one year in the future\n");
405 static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
407 struct cmos_rtc *cmos = dev_get_drvdata(dev);
408 unsigned char mon, mday, hrs, min, sec, rtc_control;
411 if (!is_valid_irq(cmos->irq))
414 ret = cmos_validate_alarm(dev, t);
418 mon = t->time.tm_mon + 1;
419 mday = t->time.tm_mday;
420 hrs = t->time.tm_hour;
421 min = t->time.tm_min;
422 sec = t->time.tm_sec;
424 rtc_control = CMOS_READ(RTC_CONTROL);
425 if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
426 /* Writing 0xff means "don't care" or "match all". */
427 mon = (mon <= 12) ? bin2bcd(mon) : 0xff;
428 mday = (mday >= 1 && mday <= 31) ? bin2bcd(mday) : 0xff;
429 hrs = (hrs < 24) ? bin2bcd(hrs) : 0xff;
430 min = (min < 60) ? bin2bcd(min) : 0xff;
431 sec = (sec < 60) ? bin2bcd(sec) : 0xff;
434 spin_lock_irq(&rtc_lock);
436 /* next rtc irq must not be from previous alarm setting */
437 cmos_irq_disable(cmos, RTC_AIE);
440 CMOS_WRITE(hrs, RTC_HOURS_ALARM);
441 CMOS_WRITE(min, RTC_MINUTES_ALARM);
442 CMOS_WRITE(sec, RTC_SECONDS_ALARM);
444 /* the system may support an "enhanced" alarm */
445 if (cmos->day_alrm) {
446 CMOS_WRITE(mday, cmos->day_alrm);
448 CMOS_WRITE(mon, cmos->mon_alrm);
451 /* FIXME the HPET alarm glue currently ignores day_alrm
454 hpet_set_alarm_time(t->time.tm_hour, t->time.tm_min, t->time.tm_sec);
457 cmos_irq_enable(cmos, RTC_AIE);
459 spin_unlock_irq(&rtc_lock);
461 cmos->alarm_expires = rtc_tm_to_time64(&t->time);
466 static int cmos_alarm_irq_enable(struct device *dev, unsigned int enabled)
468 struct cmos_rtc *cmos = dev_get_drvdata(dev);
471 if (!is_valid_irq(cmos->irq))
474 spin_lock_irqsave(&rtc_lock, flags);
477 cmos_irq_enable(cmos, RTC_AIE);
479 cmos_irq_disable(cmos, RTC_AIE);
481 spin_unlock_irqrestore(&rtc_lock, flags);
485 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
487 static int cmos_procfs(struct device *dev, struct seq_file *seq)
489 struct cmos_rtc *cmos = dev_get_drvdata(dev);
490 unsigned char rtc_control, valid;
492 spin_lock_irq(&rtc_lock);
493 rtc_control = CMOS_READ(RTC_CONTROL);
494 valid = CMOS_READ(RTC_VALID);
495 spin_unlock_irq(&rtc_lock);
497 /* NOTE: at least ICH6 reports battery status using a different
498 * (non-RTC) bit; and SQWE is ignored on many current systems.
501 "periodic_IRQ\t: %s\n"
503 "HPET_emulated\t: %s\n"
504 // "square_wave\t: %s\n"
507 "periodic_freq\t: %d\n"
508 "batt_status\t: %s\n",
509 (rtc_control & RTC_PIE) ? "yes" : "no",
510 (rtc_control & RTC_UIE) ? "yes" : "no",
511 is_hpet_enabled() ? "yes" : "no",
512 // (rtc_control & RTC_SQWE) ? "yes" : "no",
513 (rtc_control & RTC_DM_BINARY) ? "no" : "yes",
514 (rtc_control & RTC_DST_EN) ? "yes" : "no",
516 (valid & RTC_VRT) ? "okay" : "dead");
522 #define cmos_procfs NULL
525 static const struct rtc_class_ops cmos_rtc_ops = {
526 .read_time = cmos_read_time,
527 .set_time = cmos_set_time,
528 .read_alarm = cmos_read_alarm,
529 .set_alarm = cmos_set_alarm,
531 .alarm_irq_enable = cmos_alarm_irq_enable,
534 /*----------------------------------------------------------------*/
537 * All these chips have at least 64 bytes of address space, shared by
538 * RTC registers and NVRAM. Most of those bytes of NVRAM are used
539 * by boot firmware. Modern chips have 128 or 256 bytes.
542 #define NVRAM_OFFSET (RTC_REG_D + 1)
544 static int cmos_nvram_read(void *priv, unsigned int off, void *val,
547 unsigned char *buf = val;
551 spin_lock_irq(&rtc_lock);
552 for (retval = 0; count; count--, off++, retval++) {
554 *buf++ = CMOS_READ(off);
556 *buf++ = cmos_read_bank2(off);
560 spin_unlock_irq(&rtc_lock);
565 static int cmos_nvram_write(void *priv, unsigned int off, void *val,
568 struct cmos_rtc *cmos = priv;
569 unsigned char *buf = val;
572 /* NOTE: on at least PCs and Ataris, the boot firmware uses a
573 * checksum on part of the NVRAM data. That's currently ignored
574 * here. If userspace is smart enough to know what fields of
575 * NVRAM to update, updating checksums is also part of its job.
578 spin_lock_irq(&rtc_lock);
579 for (retval = 0; count; count--, off++, retval++) {
580 /* don't trash RTC registers */
581 if (off == cmos->day_alrm
582 || off == cmos->mon_alrm
583 || off == cmos->century)
586 CMOS_WRITE(*buf++, off);
588 cmos_write_bank2(*buf++, off);
592 spin_unlock_irq(&rtc_lock);
597 /*----------------------------------------------------------------*/
599 static struct cmos_rtc cmos_rtc;
601 static irqreturn_t cmos_interrupt(int irq, void *p)
606 spin_lock(&rtc_lock);
608 /* When the HPET interrupt handler calls us, the interrupt
609 * status is passed as arg1 instead of the irq number. But
610 * always clear irq status, even when HPET is in the way.
612 * Note that HPET and RTC are almost certainly out of phase,
613 * giving different IRQ status ...
615 irqstat = CMOS_READ(RTC_INTR_FLAGS);
616 rtc_control = CMOS_READ(RTC_CONTROL);
617 if (is_hpet_enabled())
618 irqstat = (unsigned long)irq & 0xF0;
620 /* If we were suspended, RTC_CONTROL may not be accurate since the
621 * bios may have cleared it.
623 if (!cmos_rtc.suspend_ctrl)
624 irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
626 irqstat &= (cmos_rtc.suspend_ctrl & RTC_IRQMASK) | RTC_IRQF;
628 /* All Linux RTC alarms should be treated as if they were oneshot.
629 * Similar code may be needed in system wakeup paths, in case the
630 * alarm woke the system.
632 if (irqstat & RTC_AIE) {
633 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
634 rtc_control &= ~RTC_AIE;
635 CMOS_WRITE(rtc_control, RTC_CONTROL);
636 hpet_mask_rtc_irq_bit(RTC_AIE);
637 CMOS_READ(RTC_INTR_FLAGS);
639 spin_unlock(&rtc_lock);
641 if (is_intr(irqstat)) {
642 rtc_update_irq(p, 1, irqstat);
652 #define INITSECTION __init
655 static int INITSECTION
656 cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
658 struct cmos_rtc_board_info *info = dev_get_platdata(dev);
660 unsigned char rtc_control;
661 unsigned address_space;
663 struct nvmem_config nvmem_cfg = {
664 .name = "cmos_nvram",
667 .reg_read = cmos_nvram_read,
668 .reg_write = cmos_nvram_write,
672 /* there can be only one ... */
679 /* Claim I/O ports ASAP, minimizing conflict with legacy driver.
681 * REVISIT non-x86 systems may instead use memory space resources
682 * (needing ioremap etc), not i/o space resources like this ...
685 ports = request_region(ports->start, resource_size(ports),
688 ports = request_mem_region(ports->start, resource_size(ports),
691 dev_dbg(dev, "i/o registers already in use\n");
695 cmos_rtc.irq = rtc_irq;
696 cmos_rtc.iomem = ports;
698 /* Heuristic to deduce NVRAM size ... do what the legacy NVRAM
699 * driver did, but don't reject unknown configs. Old hardware
700 * won't address 128 bytes. Newer chips have multiple banks,
701 * though they may not be listed in one I/O resource.
703 #if defined(CONFIG_ATARI)
705 #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) \
706 || defined(__sparc__) || defined(__mips__) \
707 || defined(__powerpc__)
710 #warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
713 if (can_bank2 && ports->end > (ports->start + 1))
716 /* For ACPI systems extension info comes from the FADT. On others,
717 * board specific setup provides it as appropriate. Systems where
718 * the alarm IRQ isn't automatically a wakeup IRQ (like ACPI, and
719 * some almost-clones) can provide hooks to make that behave.
721 * Note that ACPI doesn't preclude putting these registers into
722 * "extended" areas of the chip, including some that we won't yet
723 * expect CMOS_READ and friends to handle.
728 if (info->address_space)
729 address_space = info->address_space;
731 if (info->rtc_day_alarm && info->rtc_day_alarm < 128)
732 cmos_rtc.day_alrm = info->rtc_day_alarm;
733 if (info->rtc_mon_alarm && info->rtc_mon_alarm < 128)
734 cmos_rtc.mon_alrm = info->rtc_mon_alarm;
735 if (info->rtc_century && info->rtc_century < 128)
736 cmos_rtc.century = info->rtc_century;
738 if (info->wake_on && info->wake_off) {
739 cmos_rtc.wake_on = info->wake_on;
740 cmos_rtc.wake_off = info->wake_off;
745 dev_set_drvdata(dev, &cmos_rtc);
747 cmos_rtc.rtc = devm_rtc_allocate_device(dev);
748 if (IS_ERR(cmos_rtc.rtc)) {
749 retval = PTR_ERR(cmos_rtc.rtc);
753 rename_region(ports, dev_name(&cmos_rtc.rtc->dev));
755 spin_lock_irq(&rtc_lock);
757 if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) {
758 /* force periodic irq to CMOS reset default of 1024Hz;
760 * REVISIT it's been reported that at least one x86_64 ALI
761 * mobo doesn't use 32KHz here ... for portability we might
762 * need to do something about other clock frequencies.
764 cmos_rtc.rtc->irq_freq = 1024;
765 hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
766 CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
770 if (is_valid_irq(rtc_irq))
771 cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);
773 rtc_control = CMOS_READ(RTC_CONTROL);
775 spin_unlock_irq(&rtc_lock);
777 if (is_valid_irq(rtc_irq) && !(rtc_control & RTC_24H)) {
778 dev_warn(dev, "only 24-hr supported\n");
783 hpet_rtc_timer_init();
785 if (is_valid_irq(rtc_irq)) {
786 irq_handler_t rtc_cmos_int_handler;
788 if (is_hpet_enabled()) {
789 rtc_cmos_int_handler = hpet_rtc_interrupt;
790 retval = hpet_register_irq_handler(cmos_interrupt);
792 hpet_mask_rtc_irq_bit(RTC_IRQMASK);
793 dev_warn(dev, "hpet_register_irq_handler "
794 " failed in rtc_init().");
798 rtc_cmos_int_handler = cmos_interrupt;
800 retval = request_irq(rtc_irq, rtc_cmos_int_handler,
801 IRQF_SHARED, dev_name(&cmos_rtc.rtc->dev),
804 dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
809 cmos_rtc.rtc->ops = &cmos_rtc_ops;
810 cmos_rtc.rtc->nvram_old_abi = true;
811 retval = rtc_register_device(cmos_rtc.rtc);
815 /* export at least the first block of NVRAM */
816 nvmem_cfg.size = address_space - NVRAM_OFFSET;
817 if (rtc_nvmem_register(cmos_rtc.rtc, &nvmem_cfg))
818 dev_err(dev, "nvmem registration failed\n");
820 dev_info(dev, "%s%s, %d bytes nvram%s\n",
821 !is_valid_irq(rtc_irq) ? "no alarms" :
822 cmos_rtc.mon_alrm ? "alarms up to one year" :
823 cmos_rtc.day_alrm ? "alarms up to one month" :
824 "alarms up to one day",
825 cmos_rtc.century ? ", y3k" : "",
827 is_hpet_enabled() ? ", hpet irqs" : "");
832 if (is_valid_irq(rtc_irq))
833 free_irq(rtc_irq, cmos_rtc.rtc);
838 release_region(ports->start, resource_size(ports));
840 release_mem_region(ports->start, resource_size(ports));
844 static void cmos_do_shutdown(int rtc_irq)
846 spin_lock_irq(&rtc_lock);
847 if (is_valid_irq(rtc_irq))
848 cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
849 spin_unlock_irq(&rtc_lock);
852 static void cmos_do_remove(struct device *dev)
854 struct cmos_rtc *cmos = dev_get_drvdata(dev);
855 struct resource *ports;
857 cmos_do_shutdown(cmos->irq);
859 if (is_valid_irq(cmos->irq)) {
860 free_irq(cmos->irq, cmos->rtc);
861 hpet_unregister_irq_handler(cmos_interrupt);
868 release_region(ports->start, resource_size(ports));
870 release_mem_region(ports->start, resource_size(ports));
876 static int cmos_aie_poweroff(struct device *dev)
878 struct cmos_rtc *cmos = dev_get_drvdata(dev);
882 unsigned char rtc_control;
884 if (!cmos->alarm_expires)
887 spin_lock_irq(&rtc_lock);
888 rtc_control = CMOS_READ(RTC_CONTROL);
889 spin_unlock_irq(&rtc_lock);
891 /* We only care about the situation where AIE is disabled. */
892 if (rtc_control & RTC_AIE)
895 cmos_read_time(dev, &now);
896 t_now = rtc_tm_to_time64(&now);
899 * When enabling "RTC wake-up" in BIOS setup, the machine reboots
900 * automatically right after shutdown on some buggy boxes.
901 * This automatic rebooting issue won't happen when the alarm
902 * time is larger than now+1 seconds.
904 * If the alarm time is equal to now+1 seconds, the issue can be
905 * prevented by cancelling the alarm.
907 if (cmos->alarm_expires == t_now + 1) {
908 struct rtc_wkalrm alarm;
910 /* Cancel the AIE timer by configuring the past time. */
911 rtc_time64_to_tm(t_now - 1, &alarm.time);
913 retval = cmos_set_alarm(dev, &alarm);
914 } else if (cmos->alarm_expires > t_now + 1) {
921 static int cmos_suspend(struct device *dev)
923 struct cmos_rtc *cmos = dev_get_drvdata(dev);
926 /* only the alarm might be a wakeup event source */
927 spin_lock_irq(&rtc_lock);
928 cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
929 if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
932 if (device_may_wakeup(dev))
933 mask = RTC_IRQMASK & ~RTC_AIE;
937 CMOS_WRITE(tmp, RTC_CONTROL);
938 hpet_mask_rtc_irq_bit(mask);
940 cmos_checkintr(cmos, tmp);
942 spin_unlock_irq(&rtc_lock);
945 cmos->enabled_wake = 1;
949 enable_irq_wake(cmos->irq);
952 cmos_read_alarm(dev, &cmos->saved_wkalrm);
954 dev_dbg(dev, "suspend%s, ctrl %02x\n",
955 (tmp & RTC_AIE) ? ", alarm may wake" : "",
961 /* We want RTC alarms to wake us from e.g. ACPI G2/S5 "soft off", even
962 * after a detour through G3 "mechanical off", although the ACPI spec
963 * says wakeup should only work from G1/S4 "hibernate". To most users,
964 * distinctions between S4 and S5 are pointless. So when the hardware
965 * allows, don't draw that distinction.
967 static inline int cmos_poweroff(struct device *dev)
969 if (!IS_ENABLED(CONFIG_PM))
972 return cmos_suspend(dev);
975 static void cmos_check_wkalrm(struct device *dev)
977 struct cmos_rtc *cmos = dev_get_drvdata(dev);
978 struct rtc_wkalrm current_alarm;
979 time64_t t_current_expires;
980 time64_t t_saved_expires;
982 cmos_read_alarm(dev, ¤t_alarm);
983 t_current_expires = rtc_tm_to_time64(¤t_alarm.time);
984 t_saved_expires = rtc_tm_to_time64(&cmos->saved_wkalrm.time);
985 if (t_current_expires != t_saved_expires ||
986 cmos->saved_wkalrm.enabled != current_alarm.enabled) {
987 cmos_set_alarm(dev, &cmos->saved_wkalrm);
991 static void cmos_check_acpi_rtc_status(struct device *dev,
992 unsigned char *rtc_control);
994 static int __maybe_unused cmos_resume(struct device *dev)
996 struct cmos_rtc *cmos = dev_get_drvdata(dev);
999 if (cmos->enabled_wake) {
1001 cmos->wake_off(dev);
1003 disable_irq_wake(cmos->irq);
1004 cmos->enabled_wake = 0;
1007 /* The BIOS might have changed the alarm, restore it */
1008 cmos_check_wkalrm(dev);
1010 spin_lock_irq(&rtc_lock);
1011 tmp = cmos->suspend_ctrl;
1012 cmos->suspend_ctrl = 0;
1013 /* re-enable any irqs previously active */
1014 if (tmp & RTC_IRQMASK) {
1017 if (device_may_wakeup(dev))
1018 hpet_rtc_timer_init();
1021 CMOS_WRITE(tmp, RTC_CONTROL);
1022 hpet_set_rtc_irq_bit(tmp & RTC_IRQMASK);
1024 mask = CMOS_READ(RTC_INTR_FLAGS);
1025 mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
1026 if (!is_hpet_enabled() || !is_intr(mask))
1029 /* force one-shot behavior if HPET blocked
1030 * the wake alarm's irq
1032 rtc_update_irq(cmos->rtc, 1, mask);
1034 hpet_mask_rtc_irq_bit(RTC_AIE);
1035 } while (mask & RTC_AIE);
1038 cmos_check_acpi_rtc_status(dev, &tmp);
1040 spin_unlock_irq(&rtc_lock);
1042 dev_dbg(dev, "resume, ctrl %02x\n", tmp);
1047 static SIMPLE_DEV_PM_OPS(cmos_pm_ops, cmos_suspend, cmos_resume);
1049 /*----------------------------------------------------------------*/
1051 /* On non-x86 systems, a "CMOS" RTC lives most naturally on platform_bus.
1052 * ACPI systems always list these as PNPACPI devices, and pre-ACPI PCs
1053 * probably list them in similar PNPBIOS tables; so PNP is more common.
1055 * We don't use legacy "poke at the hardware" probing. Ancient PCs that
1056 * predate even PNPBIOS should set up platform_bus devices.
1061 #include <linux/acpi.h>
1063 static u32 rtc_handler(void *context)
1065 struct device *dev = context;
1066 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1067 unsigned char rtc_control = 0;
1068 unsigned char rtc_intr;
1069 unsigned long flags;
1071 spin_lock_irqsave(&rtc_lock, flags);
1072 if (cmos_rtc.suspend_ctrl)
1073 rtc_control = CMOS_READ(RTC_CONTROL);
1074 if (rtc_control & RTC_AIE) {
1075 cmos_rtc.suspend_ctrl &= ~RTC_AIE;
1076 CMOS_WRITE(rtc_control, RTC_CONTROL);
1077 rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
1078 rtc_update_irq(cmos->rtc, 1, rtc_intr);
1080 spin_unlock_irqrestore(&rtc_lock, flags);
1082 pm_wakeup_hard_event(dev);
1083 acpi_clear_event(ACPI_EVENT_RTC);
1084 acpi_disable_event(ACPI_EVENT_RTC, 0);
1085 return ACPI_INTERRUPT_HANDLED;
1088 static inline void rtc_wake_setup(struct device *dev)
1090 acpi_install_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler, dev);
1092 * After the RTC handler is installed, the Fixed_RTC event should
1093 * be disabled. Only when the RTC alarm is set will it be enabled.
1095 acpi_clear_event(ACPI_EVENT_RTC);
1096 acpi_disable_event(ACPI_EVENT_RTC, 0);
1099 static void rtc_wake_on(struct device *dev)
1101 acpi_clear_event(ACPI_EVENT_RTC);
1102 acpi_enable_event(ACPI_EVENT_RTC, 0);
1105 static void rtc_wake_off(struct device *dev)
1107 acpi_disable_event(ACPI_EVENT_RTC, 0);
1110 /* Every ACPI platform has a mc146818 compatible "cmos rtc". Here we find
1111 * its device node and pass extra config data. This helps its driver use
1112 * capabilities that the now-obsolete mc146818 didn't have, and informs it
1113 * that this board's RTC is wakeup-capable (per ACPI spec).
1115 static struct cmos_rtc_board_info acpi_rtc_info;
1117 static void cmos_wake_setup(struct device *dev)
1122 rtc_wake_setup(dev);
1123 acpi_rtc_info.wake_on = rtc_wake_on;
1124 acpi_rtc_info.wake_off = rtc_wake_off;
1126 /* workaround bug in some ACPI tables */
1127 if (acpi_gbl_FADT.month_alarm && !acpi_gbl_FADT.day_alarm) {
1128 dev_dbg(dev, "bogus FADT month_alarm (%d)\n",
1129 acpi_gbl_FADT.month_alarm);
1130 acpi_gbl_FADT.month_alarm = 0;
1133 acpi_rtc_info.rtc_day_alarm = acpi_gbl_FADT.day_alarm;
1134 acpi_rtc_info.rtc_mon_alarm = acpi_gbl_FADT.month_alarm;
1135 acpi_rtc_info.rtc_century = acpi_gbl_FADT.century;
1137 /* NOTE: S4_RTC_WAKE is NOT currently useful to Linux */
1138 if (acpi_gbl_FADT.flags & ACPI_FADT_S4_RTC_WAKE)
1139 dev_info(dev, "RTC can wake from S4\n");
1141 dev->platform_data = &acpi_rtc_info;
1143 /* RTC always wakes from S1/S2/S3, and often S4/STD */
1144 device_init_wakeup(dev, 1);
1147 static void cmos_check_acpi_rtc_status(struct device *dev,
1148 unsigned char *rtc_control)
1150 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1151 acpi_event_status rtc_status;
1154 if (acpi_gbl_FADT.flags & ACPI_FADT_FIXED_RTC)
1157 status = acpi_get_event_status(ACPI_EVENT_RTC, &rtc_status);
1158 if (ACPI_FAILURE(status)) {
1159 dev_err(dev, "Could not get RTC status\n");
1160 } else if (rtc_status & ACPI_EVENT_FLAG_SET) {
1162 *rtc_control &= ~RTC_AIE;
1163 CMOS_WRITE(*rtc_control, RTC_CONTROL);
1164 mask = CMOS_READ(RTC_INTR_FLAGS);
1165 rtc_update_irq(cmos->rtc, 1, mask);
1171 static void cmos_wake_setup(struct device *dev)
1175 static void cmos_check_acpi_rtc_status(struct device *dev,
1176 unsigned char *rtc_control)
1184 #include <linux/pnp.h>
1186 static int cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
1188 cmos_wake_setup(&pnp->dev);
1190 if (pnp_port_start(pnp, 0) == 0x70 && !pnp_irq_valid(pnp, 0)) {
1191 unsigned int irq = 0;
1193 /* Some machines contain a PNP entry for the RTC, but
1194 * don't define the IRQ. It should always be safe to
1195 * hardcode it on systems with a legacy PIC.
1197 if (nr_legacy_irqs())
1200 return cmos_do_probe(&pnp->dev,
1201 pnp_get_resource(pnp, IORESOURCE_IO, 0), irq);
1203 return cmos_do_probe(&pnp->dev,
1204 pnp_get_resource(pnp, IORESOURCE_IO, 0),
1209 static void cmos_pnp_remove(struct pnp_dev *pnp)
1211 cmos_do_remove(&pnp->dev);
1214 static void cmos_pnp_shutdown(struct pnp_dev *pnp)
1216 struct device *dev = &pnp->dev;
1217 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1219 if (system_state == SYSTEM_POWER_OFF) {
1220 int retval = cmos_poweroff(dev);
1222 if (cmos_aie_poweroff(dev) < 0 && !retval)
1226 cmos_do_shutdown(cmos->irq);
1229 static const struct pnp_device_id rtc_ids[] = {
1230 { .id = "PNP0b00", },
1231 { .id = "PNP0b01", },
1232 { .id = "PNP0b02", },
1235 MODULE_DEVICE_TABLE(pnp, rtc_ids);
1237 static struct pnp_driver cmos_pnp_driver = {
1238 .name = (char *) driver_name,
1239 .id_table = rtc_ids,
1240 .probe = cmos_pnp_probe,
1241 .remove = cmos_pnp_remove,
1242 .shutdown = cmos_pnp_shutdown,
1244 /* flag ensures resume() gets called, and stops syslog spam */
1245 .flags = PNP_DRIVER_RES_DO_NOT_CHANGE,
1251 #endif /* CONFIG_PNP */
1254 static const struct of_device_id of_cmos_match[] = {
1256 .compatible = "motorola,mc146818",
1260 MODULE_DEVICE_TABLE(of, of_cmos_match);
1262 static __init void cmos_of_init(struct platform_device *pdev)
1264 struct device_node *node = pdev->dev.of_node;
1270 val = of_get_property(node, "ctrl-reg", NULL);
1272 CMOS_WRITE(be32_to_cpup(val), RTC_CONTROL);
1274 val = of_get_property(node, "freq-reg", NULL);
1276 CMOS_WRITE(be32_to_cpup(val), RTC_FREQ_SELECT);
1279 static inline void cmos_of_init(struct platform_device *pdev) {}
1281 /*----------------------------------------------------------------*/
1283 /* Platform setup should have set up an RTC device, when PNP is
1284 * unavailable ... this could happen even on (older) PCs.
1287 static int __init cmos_platform_probe(struct platform_device *pdev)
1289 struct resource *resource;
1293 cmos_wake_setup(&pdev->dev);
1296 resource = platform_get_resource(pdev, IORESOURCE_IO, 0);
1298 resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
1299 irq = platform_get_irq(pdev, 0);
1303 return cmos_do_probe(&pdev->dev, resource, irq);
1306 static int cmos_platform_remove(struct platform_device *pdev)
1308 cmos_do_remove(&pdev->dev);
1312 static void cmos_platform_shutdown(struct platform_device *pdev)
1314 struct device *dev = &pdev->dev;
1315 struct cmos_rtc *cmos = dev_get_drvdata(dev);
1317 if (system_state == SYSTEM_POWER_OFF) {
1318 int retval = cmos_poweroff(dev);
1320 if (cmos_aie_poweroff(dev) < 0 && !retval)
1324 cmos_do_shutdown(cmos->irq);
1327 /* work with hotplug and coldplug */
1328 MODULE_ALIAS("platform:rtc_cmos");
1330 static struct platform_driver cmos_platform_driver = {
1331 .remove = cmos_platform_remove,
1332 .shutdown = cmos_platform_shutdown,
1334 .name = driver_name,
1336 .of_match_table = of_match_ptr(of_cmos_match),
1341 static bool pnp_driver_registered;
1343 static bool platform_driver_registered;
1345 static int __init cmos_init(void)
1350 retval = pnp_register_driver(&cmos_pnp_driver);
1352 pnp_driver_registered = true;
1355 if (!cmos_rtc.dev) {
1356 retval = platform_driver_probe(&cmos_platform_driver,
1357 cmos_platform_probe);
1359 platform_driver_registered = true;
1366 if (pnp_driver_registered)
1367 pnp_unregister_driver(&cmos_pnp_driver);
1371 module_init(cmos_init);
1373 static void __exit cmos_exit(void)
1376 if (pnp_driver_registered)
1377 pnp_unregister_driver(&cmos_pnp_driver);
1379 if (platform_driver_registered)
1380 platform_driver_unregister(&cmos_platform_driver);
1382 module_exit(cmos_exit);
1385 MODULE_AUTHOR("David Brownell");
1386 MODULE_DESCRIPTION("Driver for PC-style 'CMOS' RTCs");
1387 MODULE_LICENSE("GPL");